Metal attenuating process and apparatus



M. E. EVANS FiledA ug. 23, 1934 METAL ATTENUATING PROCESS AND APPARATUS2 Sheets-Sheet 1 ig /Ff l 3: 17 2 3. y v

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M. E, EVANS v METAL 'ATTENUATING PROCESS AND APPARATUS Filed Aug. 23,1934 2 Sheets-Sheet 2 \IJLEDW J PU E IN VENTOR.

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UUSmO wz] cwmzou uumtqIv urammwufl JEME *JLlD lw JVFUZ ZUFJOE wwu tlPatented Apr. 4, 1939 METAIi A TTENUATING PROCESS AND APPARATUS MartinE. Evans, Pittsburgh, Pa.

Application August 23, 1934, Serial No. 741,100

35 Claims.

This invention relates to an attenuated metal article and to theproduction thereof, and particularly to a duplex metal attenuatedarticle comprising a relatively high melting temperature metal and arelatively low melting temperature metal and the method of assemblingthese metals whereby new and useful metal combinations are attained andnew and useful production methods and apparatus are added to the art ofattenuating metals.

It is proposed to produce a base metal strip of relatively high meltingtemperature and of relatively high tensile strength and to control itssurface condition suitably to provide traction or attachment to anothermetal or alloy of relatively lower melting temperature positionedlongitudinally therewith.

In another aspect this invention relates to the working of a cast metalor congealed metal of small tensile strength with a metal work piece ofrelatively high tensile strength to impart pliability to the former.

In another aspect this invention relates to the production of anattenuated metal work piece adapted to receiving an addition alloyedthereto of a different analysis of metal and to the methods andapparatus specially adapted to this pur- DOSE.

in contact with the former.

The surface condition of the base metal strip is controlled by new stepsin the art of producing the strip from billetts by heating, rolling andcold working. The surface of both metalsin a combination is controlledas to chemical composition and shape.

The work piece is usually cut up into lengths and transported to variouspoints for further working. Reheating the work piece being necessary,preliminary thereto and for the protection therefrom the workpiecesurface is freed from scale by sandblasting or other means and thencoated at 200 or 300 C. with a'paint of 3 parts powdered aluminum, 5parts resin and 5 parts petroleum tar at 200 to 350 C. Also the coatingmay be of 70 parts powdered aluminum, 23 parts sal ammoniac and 7 partszinc. "In reheating to the rolling temperature, the base metal alloyswith the paint forming a protection against surface deterioration. Thesubsequent working and attenuation of the alloy with the heated basegive the alloy a degree of pliability. Obviously the attenuated baseworkpiece with such surface preparation is adapted to uniting withaluminum or zinc subsequently placed thereon in much less time than whenthe surface is free from such pre-- liminary alloy. Since the iron zincalloy is brittle and becomes thick and stiff in proportion to the timeof heating above the melting point of zinc, this control factor isimportant. Further, the penetration of the zinc by the iron and of theiron by the zinc is controlled to a degree by the character of thesurface given the work piece in the mold and by subsequent working. Theattenuated work piece may be given an alloyed coating at other points inthe reducing process 7 than as outlined. Thus, after hot rolling, theworkpiece may be cleaned and alloyed with zinc, the said alloy attaininga degree of pliability with further working. With a suitable alloysurface on the workpiece it is proposed to unite thereto a second metalsuch as aluminum or zinc in strip form or by congealing progressively.Economy in manufacture whereby handling and processing are reduced to aminimum requires that the metal be progressively congealed upon thesupport strip to provide the combination workpiece for furtherattenuation to-impart pliability to the congealed metal. However,aluminum powder or flakes mixed with zinc powder and heated in a retortto a temperature 20 to F. below the melting point of the zinc by virtueof the vapor pressure of the zinc forms an aluminum zinc alloy suitablefor union with the alloy on the work piece. After formation of thispowdered alloy the powdered zinc is separated largely therefrommechanically, and the alloy powder with the work piece is drawn througha heated die and therein united to the work piece progressively byresidual zinc powder in the alloy powder thereby forming the metalcombination.

The characteristic mobility of the coating metal provided by the moltencondition or the powdered condition of the metal is utilized to providethe distribution of the metal around the core strip.

"In the process of attenuating to a uniform cross section a duplex metalworkpiece having a relatively low strength surface layer of metal over arelatively strong support strip, the surface layer has a tendency tospread and depart from the support strip under the pressure necessary toattenuate the support. strip. To overcome this tendency it is essentialto provide means to restrain the movement of the low strength metal frommore than its proportional movement with the support strip. To this endit is proposed to apply circumferential pressure to the low strengthsurface metal to restrain its lateral movement and to govern itslongitudinal movement by engagement either frictional or bonded with thesupport strip. The circumferential restraint may be variously provided.Hydraulic pressure directly upon the workpiece is a preferred form;

engagement with an enveloping casing is another form in which instancethe casing is close fitting and of a length that bonded metal cannot besheared from the base strip but must travel with the strip through thecasing and receive its proportionate reduction in a die and emerge fromthe die into a restraining casing and travel therein jointly with thebase or support strip. Thus it is seen that the frictional or bondedengagement with the support strip should be of a length and intensity atthe approach to the attenuating device suflicient to advance the weakermetal through the attenuating means and after the exit therefromsumcient to restrain the weaker metal from longitudinal movement greaterthan that of the support strip. It is therefore evident,

that the restraint on the low strength material is completecircumferentially and longitudinally.

The apparatus chosen to effect the attenuation of the duplex stripcomprises dies or rolls or a combination preferably mounted in a chamberadapted to withstand hydraulic pressure therein of an order up to100,000 pounds per square inch. The passage of the workpiece through thechamber is effected by tension thereon, butit is intended thatadaptations having driven rolls for duplex sheets are within the scopeof this application, since the principle of restraint herein set forthis advantageously applicable thereto. The medium for applying thehydraulic pressure obviously may be of. a lubricating character, butsince the pressure is on the approach and depart-ure sides of the dieand rolls, the apparatus does not fall in the class ofunbalancedpressure lubricating devices.v

The material worked upon involves preferably a support strip that hasreceived the special operations previously outlined to provide asuitable surface condition which is progressively advanced with themolten duplex metal therearound through a congealing and working devicefor the duplex metal to an attenuatinghie or rolls. It is apparent thatduplex metal in strip form may be advanced with the support strip andunattached thereto to a die or rolls.

Referring to the drawings,

Fig. 1 shows a sectional view of a die in a casing arranged to applyhydraulic pressure on strip material passing through the die.

Fig. 2 shows an end view of the entrance die and the casing arranged forreceiving a rectangular shaped duplex metal strip section of Figure 1.

Fig. 3 shows an end view of an arrangement of rolls to replace thecentral die of Figure 1.

Figure 4 shows a sectional view of the rolls of Figure 3 with a duplexstrip between the rolls and subjected to hydraulic pressure. I

Fig. 5 shows reducing rolls supported in backing rolls mounted in apressure ring adapted to hydraulic pressure.

' Fig. 6 shows a sectional view ofrolls and mounting of Figure 5.

Fig. 7 shows another modification of the invention adapted to applypressure upon strip material passing through the central die and tocongeal (from a source not shown) metal upon a strip passingtherethrough.

Fig. 8 shows an end view of a strip folded around a core strip.

Fig. 9 shows a schematic arrangement of sources of duplex metals and theagencies employed for their treatment.

Referring particularly to Fig. 9, the schematic arrangement shows a corestrip of high strength strip is shown threaded through the congealingdevice and the reducing device to the drawing drum that providestraction.

Referring to Figure 1, within a cylindrical casing I is mounted a numberof dies 2, 3 and 4 held in pressure rings 5, Sand I respectively, inalignment in a central cylindrical chamber 8 of the casing I. On thecasing I a shoulder 9 at the exit end thereof and tapered passages I andII at the entrance end thereof accommodating a tapered key I2 withcentral eyelet I3 restrain the dies and pressure rings against axialmovement within the central chamber 8. Between the respective pressurerings 5, 6, I, gaskets I4 and form seals for chambers I6 and I1 formedon either side of the central die 3 by longitudinal extension of thecentral die pressure ring 6. A gasket I8 on the shoulder 9 of the casingadds a further seal to exit chamber I! of the central die 3. In thepressure ring 6 of the central die 3 are provided passageways I9 and 20leading from chambers I6 and I! and converging to a common conduit 2|screwed into the pressure ring 6 through a radial opening 22 in thecasing I.

kept small, and the seals I4 and I5 may be of relatively low meltingtemperature metal adapted to unite under moderate heat with the wallsforming a solid barrier. Around the central die 3 an electrical heatingelement 23 is provided in the central pressure ring 6 with a detachableconnection 24 through a continuous passage 25 in the casing I and thecentral pressure ring 6. A thermocouple thermostat 26 extends through acontinuous passage 21 in the casing I and the pressure ring 5 to contactthe central die 3.

At the exit end of the casing I is positioned a flexible hollow metalring 28 connected by a valve 29 and a pipe 30 to a dynamometer gage 40,a liquid filling the passages of the members outlined.

Extending through the registering dies 2, 3 and 4 is shown a cylindricalduplex metal strip comprising a core 32 and a covering 33 and having alarge section 34 and a reduced section 35 in chambers I6 and I1respectively.

The large section 34 of the duplex strip contacts with the taperedentrance 36 to the central die 3 and is progressively reduced thereinwhile hydraulic pressure in the chamber I6 introduced through passagesI9 and 2| forces the covering 33 against the core 32 and insures theproportionate reduction of each.

Referring to Figure 2, a' cross section of a rectangular strip 31 withthinner rectangular strips 38 and 39 on the respective sides thereof isshown entering a die 40 fitting into a pressure ring 4| positioned inthe entrance of the central chamber 8 of the casing I.

Referring to Figures 3 and 4, an embodiment of ,the inventionsubstituting rolls for dies is are held in bearings 44 and 45respectively in the pressure ring 46 which is a counterpart of theshrinkage ring 6 and adapted to replace the latter in the chamber 3 inthe casing l shown in Figure 1.

Referring to Figures 5 and 6, an embodiment of the invention is shownhaving a pair of reducing rolls 41 and 46 provided with backing rolls 49and 50 respectively mounted in cages 5| and 52 respectively andpositioried against shoulders 53 and'54 respectively in a pressure ring65 adapted to fit in the mid portion of the central chamber 8 of thecasing l. The cages 5| and 52 are held in position by liners 56 and 51respectively against radial movement, and the distance between the rolls4! and 48 is adjusted in accordance with the thickness of said liners.Changes in the thickness of the liners 56 and 51 change the position ofthe reduction rolls and the consequent reduction of the strips 53between the rolls.

Referring to Figure 7, an embodiment of the invention is presentedshowing a die 69 mounted in a pressure ring 60 having chambers 6| and 62in the extensions of said ring with screwed plugs 63 and 64 respectivelyserving to position sleeves 65 and 66 respectively which isolate thechambers 6| and 62 from the strip material 61 passing through the die59. The entering chamber 6| of the die 59 has passages 68 and 69 theretoand likewise the exit chamber 62 has passages I0 and II thereto, saidpassages being adapted to accommodate the flow of fluid therein inaccordance with operating conditions. Around. the die 53 an electricalheating element 12 is positioned in the pressure ring 63 detachablyconnected through a passage 13 in the pressure ring to a source ofelectricity.

Referring to Figure 8, a core of strip metal I4 has thereabout aclose-fitting envelope of metal 15 with an alloy of the same ordifferent metals along the line of contact I6 adapted under operativeconditions hereafter set forth to bond the combination into a solidbody.

Referring to the dual purpose device illustrated in Figure '7, a supportstrip 61 progressively adexit chamber 62 through openings I0 and 1| vlowers the temperature sufliciently to permit the coiling of thecombined strip without damage for transport to the attenuatingapparatus. The

dual purpose device of Figure 7 and the attenuating device such as shownin Figure 1 may be in tandem so that the strip material may be dividedby the central attenuating die 3 and supplied with liquid under pressurethrough pipe 2| and passages I 3 and 26. Thechambers l6 and II are of alength and the liquid therein of a pressure to restrain the surfacestrip 33 from undue lateral motion or accumulation in the reducing dieentrance 36 regardless of the bond between the support strip and thesurface strip. With the combined strip. tapered in accord with theattenuating die entrance 36 and backed out therefrom so that the taperbears against the confined fluid when the fluid acts as a die and thetaper pressing thereagainst maintains a pressure in the chamber l6. Theheater coil 23 regulated in accord with the thermostat, of which thethermocouple 26 is shown, 26 may be adjusted to heat the die 3to atemperature effecting a bond between the support strip and the surfacestrip, the die and pressure ring preferably being made of tungstencarbide to resist heat and abrasion.

The before mentioned pressure source. of molten metal may be of acharacter employed in die casting adaptedto continuous operation andparticularly to die casting of zinc and zinc alloys and aluminum to athickness of as thin as one one-hundredth of an inch. Obviously apressure source for such molten metal is not essential but preferablebecause of the density of the congealed product thereof.

The heater ring temperature adjusted in connection with the'dynamometer3| recording the pressure by the casing l on the flexible tube 26 andtransmitted by liquid through valve 29 and tube 36 in consequence of thetension on the support strip may give most favorable attenuatingoperation.

Instead of the liquid means in the pressure ring 6 for restraining themetal on the support strip from lateral movement, the device shown inFigure 7 with the tube 65 eliminated may be substituted in the casing Iand aligned therein by a simple casing not shown to fit around the ring63 and within the chamber 8 of the casing I. In that instance .the die59 performs the attenuation andthe sleeves 65 and 66 restrain metal onthe support strip against the lateral movement and accumulation in thedie entrance. The inside passages of the sleeves 66 and 66 are of alength and relative diameter in contact withstrip therein adapted toinsure the proportional flow of metal of the strip through the die 53.Where wide support strips are involved it is desirable in order toreduce friction and tension load to use rolls instead of dies and tothis end the embodiment shown in Figures 2, 3 and 4 may be usedadvantageously. The support strip 31 grouped with outside strips 38 and33 passes through an entrance die 46 in a pressure ring 4| mounted in acasing I, then through rolls 42 and 4,3 in a pressure chamber 46 andthen through an exit I die the counterpart in reduced section of theentrance die shown in Figure 2. The two dies act as glands to retain theliquid within the pressure ring. The entranceqiie, the rolls and theexit die are mounted with registering orifices. The liquid pressurewithin the shrinkage ring 46 is exerted 'die, experiments showapproximately 31% of the tension on the strip is due to friction andthat if the strip is placed in tension approximating the elastic limiton both sides of the die and such tension maintained as relative motionbetween the die and strip is produced, the force against the die duringattenuation is very materially reduced. Utilization of this principle inattenuating duplex metal strip very materially reduces the pressure ofthe attenuating die or rolls upon the metal and consequently reduces thetendency of the weaker metal to depart from proportionate reduction.Thus the congealing apparatus shown in Figure 7 operated on a duplexstrip in tandem with the apparatus in Figure 1 employs the respectivedies 59 and 2 as back tensioning means on the strip being attenuated bydie 3. This tension reduces the pressure of the die 3 upon the covering33 and the core 32, and the tendency of the covering metal 33 to departfrom proportionateentrance with the core into die 3 is materiallyreduced. This important feature is equally exemplified in theapplication of rolls to reduction of duplex strip. Thus copper andaluminum or steel and aluminum or other combinations of metals notalloyed together may be reduced in cross section and separated, with theadvantage of subjecting the weaker metal to pressing action in jointattenuation greater than the tensile strength of such weaker metal alonewould provide,--an economy in. handlingand a superior product because ofgreater density thereof resulting. Thus Babbitt metal worked on a metalstrip and separated therefrom is a new product.

To control the angle of contact between the rolls and material and toprovide the necessary support bearing, the embodiment shown in Figures 5and 6 provides attenuating rolls 4'! and 48' with backing rolls 49 and50 respectively. The use of a confined liquid atmosphere around thevarious embodiments precludes the expansion of the workpiece beyondspecified limits, limits which are prescribed by the uniformity of crosssection v in the work piece.

Referring to Figure 7, the combination of die 59 and casings 65 and 66is in effect a die having a confined approach and exit, thus providingthe restrained atmosphere. The liquid substitute'in chambers l6 and llof Fig. l for elements 65 and 66 is in effect a non-compressibleatmosphere.

To roll or draw steel and lead or steel and aluminum or steel and zincwith more than a moderate dipped coating heretofore has not beencommercially feasible because of the lack of restraint of the lowertensile strength metals mentioned. The new product from the stepsoutlined is a high tensile strength support strip and a lower strengthsurface strip jointly attenuated to a uniform cross sectio n. As anexample of a new individual product Babbitt metal may be taken ascongealed on a strip, attenuated with the strip to confer pliabilitythereon and then separated from the strip to be handled independently.

Further, the congealed metal around a high tensile strength strip may beused solely as a lubricant of a thickness to facilitate the passage ofthe strip through a greater number of dies than'any coating heretoforeavailable. Thus, as shown in Figure 1, the outer metal 33 on the strip32 may serve as a lubricant through an exceptional number of reductionsin dies.

. Substantially, as set forth, the preparatory step in protecting thesurface of -a relatively high strength metal against deleteriousaccumulations during heated attenuation as preparation for a work strip,accumulations that would tend to abrade'drawing dies and preventalloying action and the product of these steps come within the scope ofmy invention.

Obviously this inventionis not limited to the specific embodiment ofinstrumentalities, but is capable of many variations and applicationswithout departing from its spirit and scope as outlined in the followingclaims.

What is claimed, is: 1. In the process of attenuating a duplex metalstrip .one metal of which as a tendency to depart from a uniform crosssection in advance of the attenuating operation the steps consisting ofsubjecting the duplex metal strip to an attenuating operation andconstraining said duplex metal to a'path uniform in cross section at thebeginning of said attenuating operation whereby both metals areproportionately reduced in said at-- tenuating operation.

2. In duplex metal attenuating apparatus the combination of a reducingdie having an angular portion adapted to effect the reduction of duplexmetal strip by reason of said angularity, and an entrance member to saidangular portion the inner surface of which is adapted to exert lateralrestraint upon an area of duplex metal strip passing therethroughsufficient to assure proportionate metal entrance to said angularportion thereby assuring proportionate reduction of the duplex metal,and means for drawing said duplex strip through said die.

3. In duplex metal attenuating apparatus the combination of attenuatingmeans having an angular portion adapted to effect the reduction ofduplex metal strip therein by reason of pressure of said angular portionthereon, means to exert lateral pressure circumferentially upon saidstrip approaching and departing from said angular portion and withinsaid angular portion but not in contact therewith whereby said strip isconstrained to proportionate entrance, attenuation, and departure fromsaid angular portion, and means for effecting the longitudinal movementof said duplex strip through said angular portion.

4. In the process of attenuating a duplex metal strip the stepsconsisting of progressive drawing said strip through a die andprogressively maintaining a back tension somewhat below the elasticlimit of the higher strength metal of said strip while maintaining saidprogression through said die whereby pressure by said die upon saidstrip is sufficiently lowered to promote proportionate reductionof themetals of said duplex strip in said die.

5. In the process of attenuating a duplex metal strip the stepsconsisting of progressively passing said strip .through attenuatingmeans and progressively maintaining a back tension somewhat below theelastic limit of the higher strength metal of said strip whilemaintaining said progression through said attenuating means wherebypressure upon the strip by said attenuating means issufflciently loweredto promote proportionate reduction of the metals of said duplex strip bysaid attenuating means.

6. In the process of attenuating a duplex metal a strip, the stepsconsisting of progressively passing said strip through a die having atapered entrance section, progressively maintaining a back tensionsomewhat below the elastic limit of said strip while maintaining saidprogression through said die, and maintaining a lateral pressure on saidstrip at the entry to the tapered section .of said die suflic'ient toinsure the uniform entry into said die of the weaker of the duplexmetals, thereby attenuating said strip to a uniformcross section. ,r i

7. In attenuating apparatus the combination of a wire drawing die, meansto progressively pull a duplex metal strip through said die, means toprogressively maintain a tension on the strip entering said die, andmeans to guide the metal strip uniformly into the die, whereby duplexmetal of said strip is attenuated to a uniform cross section, said guidemeans being adapted to prevent bunching up of the duplex metal in frontof said die thereby assuring uniform entry of said duplex strip intosaid die.

8. In attenuating apparatus wherein duplex metal is attenuatedproportionately through the layers thereof, the combination of apressure chamber, a reducing di'e mounted in the mid portion thereof, apair of dies, one on each side of said reducing die with openings inregistry with openings of said reducing die and mounted as glands in theends of said pressure chamber, a capstan adapted to progressively draw astrip of duplex metal through said dies, and means to maintain hydraulicpressure in said chamber, said members being co-ordinated in operationso that strip material is progressively attenuated to uniform crosssection.

9. In attenuating apparatus, the combination of a tubular member with aheater ring mid section of uniform diameter, on each side of said midsection an'end section, a mounting for said tubular member forming withsaid end sections a chamber around said tubing adapted to, cool saidtubular member, an extension of said tubuceive therein molten metalaround a strip extend- "ing therethrough, and means to draw a stripthrough said tubular member,vwhereby metal is progressively congealedaround said strip in said 5 tube.

10. In combination with the inner surface of a reducing drawing die,tubular means adapted to communicate with a source of mobile coating,metal and located in advance of the drawing por- 5 tion of said die,said means having an inner surface adapted to be closely associated withthe periphery of a wire which is pulled through said die, any coatingmetal which. passes through said means in the direction of movement ofsaid wire being sufliciently free to pass to said die, so that themovement of said wire through said die accomplishes the working of saidcoating metal in said die and the adhesion of said coating metal to saidwire.

11. In combination with the inner surface of a heated reducing drawingdie, tubular means adapted to communicate with a source of mobilecoating metal and located in advance of the drawing portion of said die,said means having an inner surface adapted to be closely associated withthe periphery of a wire which is pulled through said die, any coatingmetal which passes through said means in the direction of movement ofsaid wire being sumciently free to pass to said die, so that themovement of said wire through said die accomplishes the working of saidcore metal in said die and the adhesion of said coating metal to saidwire.

12. In combination with the inner surface of a drawing die, tubularmeans adapted to communilar member-beyond said casing adapted to recatcwith a source of mobile coating metal and located in advance of thedrawing portion of said die, said means having an inner surface adaptedto be closely associated with the periphery ofa wire which is pulledthrough said die and to guide said coating metal entrained by said wirein the direction of movement of said wire. 50 that the movement of saidwire through said die accomplishes the proportionate working ofsaidcoating metal and said wire in said die and the adhesion of said coatingmetal to said wire.

13. In attenuating apparatus, the combination comprising a die with atapered entrance adapted to accommodate a work piece extendingtherethroughwith a heavy coating of relatively softer, metal, means inadvance of said tapered die entrance adapted to exert a lateralrestraint upon coating metal on a work piece for a distance suiiicientto insure longitudinal movement of said coating metal with said workpiece into said die, and means to advance said work piece in said die,whereby proportionate reduction of said work piece and its coating isobtained.

14. In attenuating apparatus, the combination comprising a die with atapered entrance adapted to accommmodate a workpiece extendingtherethrough with a relatively heavy coating of softer metal, means inadvance of said tapered die entrance adapted to exert a lateralrestraint upon a work piece for a distance suflicient to insurelongitudinalmovement of said coating metal with said work piece intosaid die, means to conand means to advance said workpiece through saidcongealing means and said die.

15. In attenuating apparatus, the combination comprising a casing, anexit reducing die and an entering positioning die in said casing inalignment, between said dies a chamber, a liquid in said chamber underpressure, the length of said chamber and the pressure of said liquidbeing so arranged as to exert a pressure upon a coating on a work strippossing tightly through said dies sufficient to insure uniform reductionin' section. of said coating and work strip as advanced in said reducingdie, and means to advance the strip through said dies.

16. In attenuating apparatus, the combination comprising a casing, apair of chambers in said casing, between said chambers a reducing die,in the outer. ends of said chambers gland-diesin alignment with saidreducing die and adapted to fit a work piece extending through saiddies, fluid in said chambers and adapted to prevent lateral movement ofcoating metal on the work piece moving through the reducing die, meansto advance the work piece through said dies, and means for applyingpressure to said fluid effective to force the coating against said workpiece.

17, In duplex metal attenuating apparatus the combination of attenuatingmeans having an angular portion adapted to efieot the reduction ofduplex metal strip by reason of pressure of said angular portionthereon, means to exert lateralrestraint upon said strip approachingsaid angular portion whereby said strip is constrained to proportionateventrance into said angular portion, means for effecting the longitudinalmovement a of said strip through said angular portion and strip with arelatively soft circumscribing metal tending to bunch up at the entranceto a reducing die, the combination comprising a die, a mounting for saiddie, and an entrance tube to said die forming therewith a continuouspassage into said die of a size adapted to hold said relatively softmetal of the strip against bunching at said die entrance.

19. In attenuating apparatus for duplex metal strip with a relativelysoft circumscribing metal tending to bunch up at the entrance to areducing die, the combination comprising a die, a mounting for said die,an entrance tube to said die forming therewith a continuous passage intosaid die of a size adapted to hold said relatively soft metal of thestrip against bunching up at said die entrance, and means to adjust saidtube in position to form said continuous passage with said die.

20. In attenuating apparatus for duplex metal strip with a relativelysoft circumscribing metal tending to bunch up at the entrance to areducing die, the combination comprising a die, a mounting for said die,an entrance tube to said die forming therewith a continuous passage intosaid die of a size adapted to hold said relatively soft metal of thestrip against bunching up at said die entrance, the ratio between thediameter of said entrance tube and the exit diameter of said dieregulating the percentage of reduction of said strip by said die.

21. In attenuating apparatus for duplex metal strip with a relativelysoft circumscribing metal tending to bunch up at the entrance to areducing die, the combination comprising a die, a mounting for said die,an entrance tube to said die forming therewith a continuous passage intosaid die of a size adapted to hold said relatively soft metal of thestrip against bunching up at said die entrance, and means to adjust saidtube in position to form said continuous passage with said die, saidindependent tube by its diameter and adjustment determining the size ofduplex wire to be attenuated.

combination of a die, an entrance tube to said die adapted to preventlateral movement of a.

duplex metal work strip drawn through said members, means to draw saidduplex metal work strip through said members, and means accommodatingthe adjustment of said entrance tube relative to said die whereby thesaid tube may be replaced as wear may require in front of said die.

23. In the process of manufacturing an attenuated duplex metal stripcomprising a core strip and a coating of softer metal thereon, the stepsconsisting of progressively forming a uniform cross section of coatingmetal on said core strip, reducing the said core and coatingproportionately by drawing them through 'a reducing die,

.and maintaining the proportionate reduction of said core and coating byprogressively guiding a 'uniform cross section of said core and coatinginto the said reducing die.

24. In the process of manufacturing an attenuated duplex stripcomprising a core strip and a coating of softer metal-thereon, the stepsconsisting of progressively 'congealing a uniform cross section ofcoating metal on saidcore strip, reducing said core and coating metalproportionately by drawing them through a die, and maintaining theproportionate reduction of said core and coating by guiding a uniformsection thereof into said reducing die.

22. In duplex metal attenuating apparatus, the

25. In the process of manufacturing an attenuated duplex metal stripcomprising a core and a coating of softer metal thereon, the stepsconmetals with temperature regulation thereof to effect the adhesion inpermanent union of said metals.

26. In combination with the innersurface of a drawing die, means adaptedto' communicate with a source of mobile coating metal located in advanceof the drawing portion of said die, means to draw a wire through saidcommunicating means and said die progressively, the inner surface ofsaid communicating means being positioned to guide a uniform perpiheralshape of coating metal entrained by said wire into said die entrance,and means to regulate the temperature of said die, whereby the coatingmetal and the wire are progressively joined and worked in said die.

27. In combination with a drawing die an entrance guide adapted to exertlateral restraint for a distance upon coating metal being propelled by acore wire into said die suitable to assure a uniform supply of saidcoating metal to said die, means to supply coating metal to said guide,and means to exert a back tension upon said core wire whereby pressureupon said coating metal is sufficiently reduced so that said coatingmetal and said core strip in reduced section emerge from said die at thesame lineal rate.

28. In combination with a drawing die an entrance guide of a lengthadapted to exert lateral restraint for a distance upon coating mate-'rial being propelled by a core strip into the die suitable to assure auniform supply of said coating material to said die, said guidepreventing intermittent bunching up of said coating material adjacentsaid die thereby assuring regular entrance of said material to said die.

29. In combination with a drawing die an entrance guide of a lengthadapted to exert lateral ,restraint for a distance upon coating materialbeing propelled by a core strip into said die suitable to assureauniform supply of said coating material to said die, said guidepreventing intermittent bunching up of said coating material adjacentsaid die thereby assuring regular entrance of said material to said die,and pressure means supplying coating material to said guide.

30. In combination with a drawing die an entrance guide of a lengthadapted to exert lateral restraint for a distance upon mobile coatingmetal being propelled with a core strip into said die suitable to assurea uniform supply of said metal to said die, said guide preventingintermittent. bunching up of said coating material adjacent said dietherebyassuring regular entrance of said material to said die.

31. In combination with a drawing die an entrance guide adopted to exertlateral restraint for a distance upon coating material being propelledby a strip into said die suitable to assure a uniform supply of saidcoating material to said die and an 'eidt guide adapted to exert lateralrestraint for a distance upon coating material suitable to assure auniform exit of said coating material from said die, and intermediatethe outer ends of said guides means to heat treat said coating material,whereby said propelling core is uniformly coated and heat treated.

32. In combination with a drawingdie heated to a temperature adapted totreat: coating metal being propelled by a core strip into said die,anentrance guide adaptgd to keep coating metal from bunching up in frontof said die and pressure means supplying coating metal to said guide.

33. In combination with mounted attenuating means such as a dieabr'acpair oirolls, means adapted to prevent intermittent bimcbingbefore said mounted means of coating metal accompanying a core stripbeing propelled through said mounted means, whereby uniform attenuationof said coating metal and core strip is assured.

34. In combination with mounted attenuating means such as a die or apair of rolls, means adapted to prevent intermittent bunching beforesaid mounted means of coating metal accompanying a core strip beingpropelled through said mounted means, and means adapted to hold saidcoating material to said core strip upon their departure from saidattenuating means, whereby said coating metal and core are uniformlyattenuated.

35. In combination with mounted attenuatin means such as a die or a pairof rolls, means adapted to prevent intermittent bunching before saidmounted means of coating material accompanying a core strip beingpropelled through said mounted means, and means adapted to hold saidcoating material to said core strip upon their departure from saidattenuating means whereby said coating material and core are uniiormlyattenuated.

MARTIN E. EVANS.

